The Monk saki (Pithecia monachus), also known as the Geoffroy's monk saki or Miller's monk saki, is a species of saki monkey, a type of New World monkey, from South America. It is found in Brazil, Colombia, Ecuador, Peru and northern Bolivia. It lives in forested areas. It can grow up to be 30–50 cm long and weigh about 1-2 kilograms, approximately the same as a large rabbit. The thick, bushy tail can be up to 25 to 55 centimeters long. It has coarse fur, which is long and shaggy around the face and neck. A shy, wary animal, it is totally arboreal, living high in the trees and sometimes descending to lower levels but not to the ground. It generally moves on all fours but may sometimes walk upright on a large branch and will leap across gaps. During the day, it moves in pairs or small family groups, feeding on fruits, berries, honey, some leaves, small mammals such as mice and bats, and birds. The female gives birth to 1 young.